private void ProcessFile(String filename)
        {
            HSSFRequest req = new HSSFRequest();
            mockListen = new MockHSSFListener();
            listener = new FormatTrackingHSSFListener(mockListen);
            req.AddListenerForAllRecords(listener);

            HSSFEventFactory factory = new HSSFEventFactory();
            try
            {
                Stream is1 = HSSFTestDataSamples.OpenSampleFileStream(filename);
                POIFSFileSystem fs = new POIFSFileSystem(is1);
                factory.ProcessWorkbookEvents(req, fs);
            }
            catch (IOException)
            {
                throw;
            }
        }
        /// <summary>
        /// Triggers the extraction.
        /// </summary>
        /// <returns></returns>
        private TextListener TriggerExtraction()
        {
            TextListener tl = new TextListener(includeSheetNames,formulasNotResults);
            FormatTrackingHSSFListener ft = new FormatTrackingHSSFListener(tl);
            tl.ft = ft;

            // Register and process
            HSSFEventFactory factory = new HSSFEventFactory();
            HSSFRequest request = new HSSFRequest();
            request.AddListenerForAllRecords(ft);

            factory.ProcessWorkbookEvents(request, fs);

            return tl;
        }